1
Scope
To form a Catalyst 3850
Data-stack and Power -stack
2
Pre-requisite
Catalyst 3850 switches can share bandwidth
by using data stacking.
§
To be able to form a switch
stack more than 2 switches must be used.
§
The IOS version used must
be the same for all switches. (Software auto upgrade can be configuring on an
existing stack to automatically upgrade newly added switches).
§
The same mode must be used
on all the switches INSTALL or BUNDLE mode
§
The right type of cables
must be used to achieve stack completion. Be aware that cables for the 3750
platform do not work on the 3850 platform.
The
following switch models do not support StackWise-480:
ü
WS-C3850-48XS-S
ü
WS-C3850-48XS-E
ü
WS-C3850-48XS-F-S
ü
WS-C3850-48XS-F-E
2.1 Components Used
§
Cisco Catalyst 3850
switches.
§
Cisco 3850 Stack wise
cables.
§
Cisco 3850 stack power
cables.
2.2 Switch Stacking and Power Stacking Guidelines
Before connecting the switches in a stack,
keep in mind these stacking guidelines:
§
Size of the switch and any
optional power-supply module. The 1100-W power-supply module is longer than the
other modules. Stacking switches with the same power-supply modules together
makes it easier to cable the switches.
§
Length of cable. Depending
on the configurations that you have, you might need different-sized cables. If
you do not specify the length of the Stack Wise cable, the 0.5-meter cable is
supplied. If you need the 1-meter cable or the 3-meter cable, you can order it
from your Cisco supplier. For cable part numbers, see Stack Wise Ports. The
Data Stack Cabling Configurations provides examples of recommended
configurations.
§
For rack-mounted switch
stacks that are members of a Stack Power stack as well as a data stack, see
Planning a Stack Power Stack.
§
You can create data stacks
with up to nine switches in a stack.
§
The Catalyst WS-C3850-48XS
switch models do not support power stacking.
3
Procedure
Start of Procedure
3.1 Network Diagram
The example below, shows how to properly connect a stack of
six 3850 switches, together with a power-stack connection example.
Note: The process will be similar for stacks of 2,3,4,5,7,8
and 9 switches.
Each switch has two stack-wise ports(left), let's name the
stack wise ports P1 and P2 as shown in the picture.
switch_1 P1 connects to switch_2 P2 (Green cable)
switch_2 P1 connects to switch_3 P2 (Orange cable)
switch_3 P1 connects to switch_4 P2 (Purple cable)
switch_4 P1 connects to switch_5 P2 (Violet cable)
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3.2 Below the steps that show how to cable the stack for power-stack
configuration:
Stack Power is a feature that allows the power supplies to
share the load across multiple devices in a stack. By connecting the switches
with power stack cables, the power supplies of up to four stack members can be
managed as a one large power supply that provides power to all switches and to
the powered devices connected to switch ports.
Each switch has two power-stack ports, let’s call the ports
A and B ( A top, B bottom)
·
From switch 1 port A we
connect to switch 2 port B (pink cable).
·
From switch 1 port B we
connect to switch 4 port A (pale green cable)
·
From switch 2 port A we
connect to switch 3 port B (blue cable)
·
From switch 3 port A we
connect to switch 4 port B (red cable)
·
From switch 5 port A we
connect to switch 6 port B (Red cable).
·
From switch 6 port A we
connect to switch 5 port B (pale blue cable)
Note: Be aware that currently up to four switches can be
used on a power-stack configuration and up to nine for a data stack.
3.3 Adding a switch to the stack
The switch to be added to the stack must be off. Otherwise,
the hole stack will reload.
1.- Add the new switch to the stack by connecting the stack
cables to the switch (every cable has a cisco logo on the connector, it must be
in the upright position) as shown in the picture below (1):
2.- Once the stack-wise cables
have been properly connected to the switch, power on the newly added switch
either using the power supplies or the power-stack cables
3.4 Switch Stack Membership
A standalone switch is a switch stack with one stack member
that also operates as the active switch. You can connect one standalone switch
to another to create a switch stack containing two stack members, with one of
them as the active switch. You can connect standalone switches to an existing
switch stack to increase the stack membership.
3.4.1
Changes to Switch Stack Membership
If you replace a stack member with an identical model, the
new switch functions with exactly the same configuration as the replaced
switch, assuming that the new switch (referred to as the provisioned switch) is
using the same member number as the replaced switch.
The operation of the switch stack continues uninterrupted
during membership changes unless you remove the active switch, or you add
powered-on standalone switches or switch stacks.
Adding powered-on switches (merging) causes all switches to
reload and elect a new active switch from among themselves. The newly elected
active switch retains its role and configuration. All other switches retain
their stack member numbers and use the stack configuration of the newly elected
active switch.
·
Removing powered-on stack
members causes the switch stack to divide (partition) into two or more switch
stacks, each with the same configuration. This can cause:
o
An IP address conflict in
your network. If you want the switch stacks to remain separate, change the IP
address or addresses of the newly created switch stacks.
o
A MAC address conflict
between two members in the stack. You can use the stack-mac update force
command to resolve the conflict.
If a newly created switch stack does not have an active
switch or standby switch, the switch stack will reload and elect a new active
switch.
If you remove powered-on members but do not want to
partition the stack:
·
Power off the switches in
the newly created switch stacks.
·
Reconnect them to the
original switch stack through their stack ports.
·
Power on the switches.
3.5 Stack Member Numbers
he stack member number (1 to 9) identifies each member in
the switch stack. The member number also determines the interface-level
configuration that a stack member uses. You can display the stack member number
by using the show switch EXEC command.
A new, out-of-the-box switch (one that has not joined a
switch stack or has not been manually assigned a stack member number) ships
with a default stack member number of 1. When it joins a switch stack, its
default stack member number changes to the lowest available member number in
the stack.
Stack members in the same switch stack cannot have the same
stack member number. Every stack member, including a standalone switch, retains
its member number until you manually change the number or unless the number is
already being used by another member in the stack.
·
If you manually change the
stack member number by using the switch current-stack-member-number renumber
new-stack-member-number EXEC command, the new number goes into effect after
that stack member resets (or after you use the reload slot stack-member-number
privileged EXEC command) and only if that number is not already assigned to any
other members in the stack. Another way to change the stack member number is by
changing the SWITCH_NUMBER environment variable.
If the number is being used by another
member in the stack, the switch selects the lowest available number in the
stack.
If you manually change the number of a
stack member and no interface-level configuration is associated with that new
member number, that stack member resets to its default configuration.
You cannot use the switch
current-stack-member-number renumber new-stack-member-number EXEC command on a
provisioned switch. If you do, the command is rejected.
·
If you move a stack member
to a different switch stack, the stack member retains its number only if the
number is not being used by another member in the stack. If it is being used,
the switch selects the lowest available number in the stack.
·
If you merge switch stacks,
the switches that join the switch stack of a new active switch select the
lowest available numbers in the stack.
3.6 Stack Member Priority Values
A higher priority value for a stack member increases the
probability of it being elected active switch and retaining its stack member
number. The priority value can be 1 to 15. The default priority value is 1. You
can display the stack member priority value by using the show switch EXEC
command.
To change the priority value for a stack member, use the switch
stack-member-number priority new priority-value EXEC command.
The new priority value takes effect immediately but does not
affect the current active switch. The new priority value helps determine which
stack member is elected as the new active switch when the current active switch
or the switch stack resets.
3.7 How to Configure a Switch Stack
3.7.1
Default Switch Stack Configuration
The following table shows the default switch stack
configuration settings:
|
Feature |
Default Setting |
|
Stack MAC
address timer |
Disabled. |
|
Stack member
number |
1 |
|
Stack member
priority value |
1 |
|
Offline
configuration |
The switch
stack is not provisioned. |
|
Persistent MAC
address |
Disabled. |
3.7.2
Enabling the Persistent MAC Address Feature
This procedure is optional.
When you enter the command to configure this feature, a
warning message appears with the consequences of your configuration. You should
use this feature cautiously. Using the old active switch MAC address elsewhere
in the same domain could result in lost traffic.
SUMMARY STEPS
1.
configure terminal
2.
stack-mac persistent timer [0 | time-value]
3.
end
4.
copy running-config startup-config
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
configure terminal Example: Switch# configure terminal |
Enters global configuration mode. |
|
Step 2 |
stack-macpersistenttimer [0 | time-value] Example: Switch(config)# stack-mac persistent timer 7 |
Enables a time delay after an
active-switch change before the stack MAC address changes to that of the new
active switch. If the previous active switch rejoins the stack during this
period, the stack uses that MAC address as the stack MAC address. • Enter the command with no value or with a value of 0 to continue using the
MAC address of the current active switch indefinitely. • Enter a time-value
from 1 to 60 minutes to configure the time period before the stack
MAC address changes to the new active switch. The stack MAC address of the
previous active switch is used until the configured time period expires. |
|
Step 3 |
end Example: Switch(config)# end |
Returns to privileged EXEC mode. |
|
Step 4 |
copy running-config startup-config Example: Switch# copy running-config startup-config |
(Optional) Saves your entries in the
configuration file. |
3.7.3
Assigning a Stack Member Number
This optional task is available only from the active switch.
SUMMARY STEPS
1.
switch current-stack-member-number
renumber new-stack-member-number
2.
reload slot stack-member-number
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
switch
current-stack-member-number
renumber new-stack-member-number |
Specifies the current stack member
number and the new stack member number for the stack member. The range is 1
to 9. |
|
|
Example: Switch# switch 3 renumber 4 |
You can display the current stack
member number by using the show
switch user EXEC command. |
|
Step 2 |
reload slot stack-member-number Example: Switch# reload slot 4 |
Resets the stack member. |
3.7.4
Setting the Stack Member Priority Value
This optional task is available only from the active switch.
Follow these steps to assign a priority value to a stack
member:
SUMMARY STEPS
1.
enable
2.
switch stack-member-number
priority new-priority-number
3.
show switch stack-member-number
4.
copy running-config startup-config
5.
copy running-config startup-config
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
enable Example: Switch enable |
Enables privileged EXEC mode. Enter
your password if prompted. |
Provisioning
a New Member for a Switch Stack
|
|
Command or Action |
Purpose |
|
Step 2 |
switch stack-member-number
priority new-priority-number Example: Switch# switch 3 priority 2 |
Specifies the stack member number
and the new priority for the stack member. The stack member number range is 1
to 9. The priority value range is 1 to 15. You can display the current
priority value by using the show
switch user EXEC command. The new priority value takes effect
immediately but does not affect the current active switch. The new priority
value helps determine which stack member is elected as the new active switch
when the current active switch or switch stack resets. |
|
Step 3 |
show switch stack-member-number Example: Switch# show switch |
Verify the stack member priority
value. |
|
Step 4 |
copy running-config startup-config Example: Switch# copy running-config startup-config |
(Optional) Saves your entries in the
configuration file. |
3.7.5
Provisioning a New Member for a Switch Stack
This optional task is available only from the active switch.
SUMMARY STEPS
1.
show switch
2.
configure terminal
3.
switch stack-member-number
provision type
4.
end
5.
copy running-config startup-config
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
show switch Example: Switch# show switch |
Displays summary information about
the switch stack. |
|
Step 2 |
configure terminal Example: Switch# configure terminal |
Enters global configuration mode. |
|
Step 3 |
switch stack-member-number
provision type Example: Switch(config)# switch 3 provision WS-xxxx |
Specifies the stack member number
for the preconfigured switch. By default, no switches are provisioned. For stack-member-number, the range is 1 to 9.
Specify a stack member number that is not already used in the switch stack.
See Step 1. For type, enter the model number of a supported switch
that is listed in the command-line help strings. |
|
Step 4 |
end Example: Switch(config)# end |
Returns to privileged EXEC mode. |
3.7.6
Removing Provisioned Switch Information
Before you begin, you must remove the provisioned switch
from the stack. This optional task is available only from the active switch.
SUMMARY STEPS
1.
configure terminal
2.
no switch stack-member-number
provision
3.
end
4.
copy running-config startup-config
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
configure terminal Example: Switch# configure terminal |
Enters global configuration mode. |
|
Step 2 |
no switch stack-member-number
provision Example: Switch(config)# no switch 3 provision |
Removes the provisioning information
for the specified member. |
|
Step 3 |
end Example: Switch(config)# end |
Returns to privileged EXEC mode. |
|
Step 4 |
copy running-config startup-config Example: Switch# copy running-config startup-config |
(Optional) Saves your entries in the
configuration file. |
If you are removing a provisioned switch in a stack with
this configuration:
• The stack
has four members
• Stack
member 1 is the active switch
• Stack
member 3 is a provisioned switch
and want to remove the provisioned information and to avoid
receiving an error message, you can remove power from stack member 3,
disconnect the StackWise-480 cables between the stack member 3 and switches to
which it is connected, reconnect the cables between the remaining stack
members, and enter the no switch stack-member-number provision global
configuration command.
3.7.7
Displaying Incompatible Switches in the Switch Stack
SUMMARY STEPS
1.
show switch
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
show switch Example: Switch# show switch |
Displays any incompatible switches
in the switch stack (indicated by a 'Current State' of 'V-Mismatch'). The
V-Mismatch state identifies the switches with incompatible software. The
output displays Lic-Mismatch for switches that are not running the same
license level as the active switch. For information about managing
license levels, see the SystemManagementConfiguration
Guide (Catalyst 3850 Switches). |
3.7.8
Upgrading an Incompatible Switch in the Switch Stack
SUMMARY STEPS
1.
software auto-upgrade
2.
copy running-config startup-config
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
software auto-upgrade Example: Switch# software auto-upgrade |
Upgrades incompatible switches in the
switch stack, or changes switches in bundle mode to installed mode. |
|
Step 2 |
copy running-config startup-config Example: Switch# copy running-config startup-config |
(Optional) Saves your entries in the
configuration file. |
3.8 Verify
After the switch has come up, collect the following:
* show
switch
* show
switch stack-ports
* show
version
On the show switch output verify that the current state
of all switches is READY.
Switch#show switch
Switch/Stack Mac Address : 6400.f125.1b80 - Local Mac
Address
Mac persistency wait time: Indefinite
H/W Current
Switch# Role Mac Address Priority Version
State
---------------------------------------------------------------------------------------------------------
*1
Active 6400.f125.1b80 15 0
Ready
2
Standby 6400.f155.1dF0 14 0
Ready
On the show switch stack-ports verify that all the ports
are shown as OK, that is an indication that the stack-wise cables are working
properly:
Switch#show switch stack-ports
Switch # Port 1 Port 2
-------- ------ ------
1
OK OK
2
OK OK
3
OK OK
4
OK OK
5
OK OK
6
OK OK
With the show version command, verify that all the
switches on the stack have the same IOS version installed and that all of them
have the same mode install or bundle.
Switch Ports Model SW Version SW Image Mode
------ - ------ ------------------------ ----------------------- --------------------------------
1 56
WS-C3850-48P
03.02.03.SE cat3k_caa-universalk9 INSTALL
2 56
WS-C3850-48P
03.02.03.SE cat3k_caa-universalk9 INSTALL
3 56
WS-C3850-48P
03.02.03.SE cat3k_caa-universalk9 INSTALL
3.9 Troubleshoot
The stack might not form properly, this can be due to
several reasons. Below there are some of the most common situations showing why
a stack does not form properly.
This can be due to a cable not properly connected or to a
faulty stack port on the switch:
Make sure that the cable logo (Cisco logo) is in the upright
position on both ends of the cable.
Make sure the cable is plugged in correctly and is not
loose.
It can be due to a version mismatch, make sure that all
the switches on the stack have the same IOS image.
The auto-upgrade feature can be configured so every time a
switch is added to the stack this will be automatically upgraded to the IOS
version used on the stack.
#sh switch
Switch# Role Mac Address Priority Version State
--------------------------------------------------------------------------------------------------------------------
*1
Active 6400.f125.1480 15 V01 Ready
2
Standby 6400.f125.2680 14 0 V-Mismatch
3
Member 6400.f125.2500 13 0 V-Mismatch
4
Member 6400.f125.2480 12 0 V-Mismatch
It might be due to a license version mismatch, verify
that all the switches on the stack have the same license level.
The license level can be verified with the show license-right-to.
Use command.
#show switch
Switch# Role Mac Address Priority Version State
----------------------------------------------------------------------------------------------------------------------
*1
Active
6400.f125.1480 15 V01 Ready
2 Standby
6400.f125.2680 14 V01 Ready
3
Member 6400.f125.2500 13 V01 Ready
4
Member 6400.f125.2480
3.9.1
Accessing the Diagnostic Console of a Stack Member
This optional task is available only from the active switch.
SUMMARY STEPS
1.
session switch stack-member-number
2.
exit
3.9.2
Temporarily Disabling a Stack Port
If a stack port is flapping and causing instability in the
stack ring, to disable the port, enter the switch stack-member-number
stack port port-number disable privileged EXEC command. To
reenable the port, enter the switch stack-member-number stack
port port-number enable command.
Be careful when using the switch stack-member-number
stackport port-number disable command. When you
disable the stack port, the stack operates at half bandwidth.
A stack is in the full-ring state when all members are
connected through the stack ports and are in the ready state.
The stack is in the partial-ring state when the following
occurs:
• All
members are connected through their stack ports but some are not in the ready
state.
• Some
members are not connected through the stack ports.
SUMMARY STEPS
1. switch stack-member-number stack port port-number disable
2.
switch stack-member-number
stack port port-number enable
DETAILED STEPS
|
|
Command or Action |
Purpose |
|
Step 1 |
switch stack-member-number
stack port
port-number
disable Example: Switch# switch 2 stack port 1 disable |
Disables the specified stack port. |
|
Step 2 |
switch stack-member-number
stack port
port-number
enable Example: Switch# switch 2 stack port 1 enable |
Reenables the stack port. |
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